Short term relief but long term drought persists

Autumn rainfall was average to above average over much of inland NSW,
northern and western Victoria, Tasmania and southern South Australia,
thereby providing some short-term relief to many agricultural systems
and an easing of the severe drought caused in part by the 2006/07 El
Niño event. However, some areas missed out, most notably eastern
Queensland, southern Victoria (especially around Melbourne) and western
WA.

An important consideration in the recovery from drought is the different
rate at which systems respond to rainfall deficiencies. At the current
time, many catchments in eastern Australia are excessively dry from a
very protracted period of below average rainfall and above average
temperatures. This means that it will take above average rainfall just
to produce average runoff, and very considerable rainfall to make a
material difference to water storages.

12-month rainfall deficiencies

Long term deficiencies remain in parts of western and eastern Australia

Average to above average rainfall during May in NSW, Victoria and
Tasmania eased the intensity and extent of 12-month rainfall deficits
in comparison with the situation at the end of April, but
severe deficiencies
still remain. In contrast, below average rainfall in WA saw
little or no improvement in that State.

For the 12-month period from June 2006 to
May 2007, there were serious
to severe rainfall deficiencies over southern and eastern Australia in
an arc extending across southeastern SA, much of southern and eastern
Victoria, and the tablelands and western slopes in southeastern NSW. A
large part of southeast Queensland was also affected, as were northern
and eastern Tasmania and WA west of a line from Dampier in the north to
Bremer Bay in the south. Record low 12-month falls were recorded between
Dalby and Goondiwindi in southern Queensland, near much of WA’s west
coast, in northeast Tasmania and in a large area around Melbourne.

The worst of the long-term deficiencies are likely to remain for some
time. For them to be removed by the end of August, for example, falls
over the next three months would need to be in the highest 10% of the
historical record in many areas, especially in Victoria and southeast
Queensland.

The deficiencies discussed above have occurred against a backdrop of
multi-year rainfall deficits that have severely stressed water supplies
in the east and southwest of the country.